I agree that the timelines don't add up. However, I think it's a case of the year dates being inconsistent with the "we've been together two years" types of comments.

I...think...perhaps...the writers started dropping in specific years without really thinking about the other time periods which had been mentioned in Flashes Before Your Eyes.

Sort of like after Walkabout. The flashbacks suddenly have him with a comb-over hairstyle but you don't really know how far back in Locke's life they are taking this. So we have Locke donating a kidney, stalking his father, going to group therapy for a year, becoming a house inspector (and seeing Nadia in the U.S.), joining a commune, and running guns...all before he was pushed out a window by his father four years before Flight 815. So...how many years of Locke's history have we been shown?

Another problem with Desmond's timeline is they still have to fit in his stint in the Armed Forces and imprisonment. Obviously it comes after 1995-6, but there isn't much time left (I think) to fit in his training, his trial, and his imprisonment. And didn't Whitmore tell him about the round-the-world boat race just before Desmond asked if he could marry Penny (in Flashes Before Your Eyes)? Where would the soldiering and prison time fit in between that flashback and his entering the race?

That could be another inconsistency.

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charlie98210
"Whoa!" she said. "Cry 'Havoc!' And let loose the dogs of war!"
And, like Banquo's ghost, they just won't go away.